JP2001260247A - Method for manufacturing pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a carcass cord pass uniform so as to improve the uniformity of a pneumatic tire. SOLUTION: First, the protruding part A2 of a wound body A of a tire constituent member(a) is constricted into a cylindrical shape of a smell diameter and at least a part of the body part A1 is brought into pressure contact with a molding drum 1 across its entire periphery with the use of a retainer 2 arranged in a freely attachable/detachable manner, prior to a bead core mounting process P3 for fitting a bead core C to be inserted from the outer end side of the protending part A2, into both sides of the body part A1 of the wound body A and thus the body part A1 is firmly held so that it does not move.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a pneumatic tire capable of uniformizing a carcass cord path between bead cores and improving uniformity.

[0002]

2. Description of the Related Art Conventionally, when a tire raw cover is formed by using a forming drum having an outer diameter larger than the inner diameter of a bead core, as shown in FIGS. The tire constituent member a including the carcass ply is wound on the forming drum B, thereby forming a straight cylindrical winding body A whose both ends protrude from the forming drum B.

Thereafter, the protruding portion A2 of the wound body A
Of the tire component a by pressing the bead cores C inserted from the outer ends thereof inwardly and pressing them against the outer end surface of the drum B.
The bead core C is fixed to the outer end face of the drum B using the rubber adhesive force of the above.

Here, the narrowing-down to the protruding portion A2 is usually performed by a narrowing-down jig F having a plurality of vertically movable leaf spring pieces f having one end pivotally mounted on the same circumference as shown in FIG.
The leaf spring pieces f are made to fall down from the standing state by using the protruding portion A2 due to the falling force or the like.
Is narrowed down to a small diameter.

[0005] Such narrowing and pressing of the bead core C against the outer end surface of the drum B are performed substantially simultaneously on both the left and right sides.

[0006]

Strictly speaking, however, the timing of the fall of the leaf spring piece f and the gap g between the leaf spring piece f and the forming drum B have variations on the left and right. Further, in each leaf spring piece f, there is a variation in the drawing-in force.

As a result, the carcass ply may meander, and the carcass cord path between the bead cores C, C may become non-uniform in the circumferential direction, thereby lowering the uniformity of the tire. That is, for example, in the left and right leaf spring pieces f, f, the side on which it quickly falls down (FIG. 8A)
), The side where the pressing force is strong (FIG. 8B), or the interval g
The carcass ply is partially pulled toward the side where is smaller (FIG. 8 (C)), and is displaced in the direction of the arrow. Therefore, as shown exaggeratedly in FIG. 9, the carcass ply is meandered in the tire axial direction. Further, at this time, since the cord interval becomes narrow on the side where the cord is pulled, the cord angle varies, and the cord path between the bead cores C, C becomes uneven.

Therefore, the present invention is based on the fact that at least a part of the wound body is pressed against and held on the forming drum over the entire circumference prior to narrowing to the protruding portion. It is another object of the present invention to provide a method for manufacturing a pneumatic tire that can prevent the carcass ply from being displaced, suppress the meandering of the carcass ply, make the code path uniform, and improve the uniformity.

[0009]

In order to achieve the above object, the invention of a method for manufacturing a pneumatic tire according to claim 1 of the present invention provides an inner liner sheet and a carcass ply on a cylindrical forming drum capable of expanding and contracting. And wound around a tire constituent member wider than the forming drum, so as to be divided into a main body portion on the forming drum and a protruding portion protruding from an outer end of the forming drum. And a main body portion holding at least a part of the main body portion pressed against the forming drum over the entire circumference and immovably in the axial direction by using a detachable holding tool. A bead core mounting step of, after reducing the protruding portion of the wound body into a small-diameter tubular shape, loosely inserting a bead core from the outer end side onto the protruding portion and mounting the bead core on both sides of the main body portion, Installation work After removing the holding tool from the main body, and forming a tire raw cover by folding the protruding portion around the bead core and expanding the main body between the bead cores. Features.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of the present invention will be described.
This will be described together with the illustrated example. The manufacturing method of the pneumatic tire of the present invention (may be simply referred to as a manufacturing method) is shown in FIGS.
As shown in FIG. 1, a winding member forming step P1 (FIG. 1) in which a tire component a including an inner liner sheet and a carcass ply is wound around a forming drum 1 to form a right cylindrical cylindrical winding member A.
(A)), and a main body holding step P2 (FIG. 1 (B)) for holding at least a part of the main body A1 of the wound body A by pressing and holding the forming drum 1 using the holder 2; A bead core mounting step P3 of narrowing the protruding portion A2 of the wound body A into a small-diameter cylindrical shape, and mounting bead cores C to be inserted from the outer ends thereof on both sides of the main body portion A1.
(FIGS. 2 (A) and 2 (B)), after that, a holder removing step P4 for removing the holder 2 from the main body part A1, and the protruding part A2 is turned around the bead core C and the main body part A1 is bead core. A molding step P5 (FIGS. 3A and 3B) for molding the tire raw cover 10 by expanding between C and C is provided.

Here, the forming drum 1 used in the present invention is
A well-known conventional structure can be suitably used. That is, as schematically illustrated in FIG. 4, the outer peripheral surface 1 </ b> S of the forming drum 1 has a substantially right cylindrical shape, and is rotatably supported by the support shaft 3. In order to make the wound body A formed on the outer peripheral surface 1S detachable, a diameter-reducible structure using a plurality of segments 4 divided in the circumferential direction is adopted. The outer diameter of the forming drum 1 is larger than the inner diameter of the bead core C. Therefore, the setting of the bead core C is performed at the outer end position of the forming drum 1.

In this embodiment, on both outer sides of the forming drum 1,
In the forming step P5, the protruding portion A2 of the wound body A
An example in which a well-known turn-up means 5 having a bladder 5A for folding back is provided.

Next, in the wound body forming step P1, the tire constituting member a is wound on the forming drum 1 to form a straight cylindrical wound body A. At this time, the winding member A is formed by making the tire constituent member a wider than the forming drum 1.
Are divided into a main body portion A1 on the forming drum 1 and a protruding portion A2 protruding from the outer end of the forming drum 1.

In the winding, the forming drum 1 is rotated at a low speed, and is usually wound one by one. For example, after the inner liner sheet and the carcass ply are laminated in a sheet shape in advance, The superposed body may be wound at a time to form a wound body A.

In the main body holding step P2, at least a part of the main body A1 is pressed against the forming drum 1 over the entire circumference by using a holder 2 which is detachably provided, and is axially and circumferentially pressed. Keep immovable.

The holder 2 is not particularly restricted in the present application, but may be, for example, a band-shaped tightening band that is wound around the main body A1 to tighten the main body A1. Further, as schematically shown in FIG. 5, it may be formed by a plurality of segments 6 which become cylindrical by moving inward in the radial direction and are capable of expanding and contracting to press the main body portion A1 against the forming drum 1.

The holding position of the holder 2 is preferably at the approximate center of the main body A1 if it is located at one place as in the present embodiment, and the outer ends of the main body A1 at two places. It is preferable that the holding width W2 of the holder 2 be 0.3 times or more the width W1 of the main body A1 in order to more reliably prevent the main body A1 from moving in the axial and circumferential directions.

Further, the bead core mounting step P3 is the same as that shown in FIG.
(A) and (B), a squeezing step P3A for reducing the protruding portion A2 into a small-diameter cylindrical shape, and a bead core C being loosely inserted into the protruding portion A2 from the outer end side thereof. A mounting process P3B for mounting on both sides of A1 is provided.

The squeezing step P3A and the mounting step P3B are substantially the same as those in the prior art. In particular, in the squeezing step P3A, as shown in FIG. The attached narrowing jig F can be suitably used as in the related art. Further, in this example, an example is shown in which an unvulcanized bead apex rubber having a triangular cross section is integrally attached to the outer peripheral surface of the bead core C in advance.

The holder removing step P4 is a step of removing the holder 2 from the main body A1, and is performed after the mounting step P3B is completed.

The molding step P5 is also performed as shown in FIG.
As shown in (B), the structure is substantially the same as that of the related art. In this example, the cylindrical folded body 9 is formed by using the turn-up means 5 and folding the protruding portion A2 around the bead core C. A folding step P5A to be formed, and the main body portion A1 is expanded in a toroidal shape between the bead cores C, C, and a tread component T including a belt T1, a tread rubber T2, and the like is attached to the crown portion, and the tire raw cover is formed. Tire raw cover forming step P5 for forming the tire 10
B is exemplified. Then, the tire raw cover 10 is vulcanized and molded to produce a pneumatic tire.

As the molding step P5, a so-called one-stage molding apparatus can be used to simultaneously carry out the folding step P5A and the raw tire cover forming step P5B.

As described above, in the present application, prior to the bead core mounting step P3, at least a part of the main body portion A1 is pressed against the forming drum 1 over the entire circumference using the holder 2, and the axial direction and the circumferential direction are used. Is held immovable.

Therefore, when narrowing the protruding portion A2, when the narrowing-down jig F falls down and the interval g between the narrowing-down jig F and the forming drum B have a variation on the left and right, Even when there is a variation in the narrowing-down force in the piece f, it is possible to prevent the positional deviation of the carcass ply.

As a result, meandering of the carcass ply and variation in the carcass cord path between the bead cores C, C can be effectively suppressed, and the uniformity of the tire can be improved.

Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the illustrated embodiment, but may be implemented in various forms.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A tire having a size of 1
Prototype of a 95 / 65R15 radial tire for passenger cars,
The variation of the carcass cord path between the bead cores of each test tire and the RFV (radial force variation) were measured.

The variation of the carcass code path is obtained by measuring the code paths at eight locations in the circumferential direction, and calculating the average deviation of each data,
And standard deviation (σ) were compared.

The RFV is measured in accordance with JASO C607 (Method for testing uniformity of automobile tires).
The average value and the standard deviation (σ) of each data of ten tires were compared.

[0030]

[Table 1]

It was confirmed that the product of the example had improved uniformity as compared with the conventional product.

[0032]

Since the present invention is configured as described above,
The carcass cord path is made uniform, and the uniformity of the tire can be improved.

[Brief description of the drawings]

FIGS. 1A and 1B are schematic views showing one embodiment of a wound body forming step and a main body holding step in the present invention.

FIGS. 2A and 2B are schematic views showing one embodiment of a bead core mounting step in the present invention.

FIGS. 3A and 3B are schematic views showing one embodiment of a molding step in the present invention.

FIG. 4 is a front view showing an example of a forming drum.

FIG. 5 is a conceptual diagram illustrating an example of a holder.

FIG. 6 is a perspective view showing an example of a narrowing jig.

FIGS. 7A to 7C are conceptual diagrams illustrating a conventional tire manufacturing method.

FIGS. 8A to 8C are conceptual diagrams for explaining the cause of the problem of the related art.

FIG. 9 is a conceptual diagram illustrating a problem of the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Forming drum 2 Holder 10 Tire raw cover a Tire constituent member A Winding body A1 Body part A2 Protruding part C Bead core

Claims (1)

[Claims] 1. A main body on a forming drum, which is formed by winding a tire forming member including an inner liner sheet and a carcass ply and having a width wider than the forming drum on a cylindrical forming drum capable of expanding and contracting. A winding body forming a straight cylindrical winding body that is divided into a cylindrical portion and a protruding portion protruding from the outer end of the forming drum; and at least one of the main body portions using a detachably disposed holder. Main body portion holding step in which the portion is pressed against the forming drum over the entire circumference and is immovably held in the axial direction and the circumferential direction, and after the protrusion portion of the wound body is reduced in diameter to a small-diameter cylindrical shape, the protrusion portion is formed. A bead core mounting step of loosely inserting a bead core from the outer end side thereof and mounting the bead core on both sides of the main body part; a holding tool removing step of removing the holding tool from the main body part after the bead core mounting step; Method for producing a pneumatic tire comprising a forming step of forming a tire raw cover by the folded and the main body portion around a bead core inflating between the bead cores.